[exim] Redirect router help (rewrite 'to' and 'subject')

Hi. I'm trying to configure a router so that mail sent to faxout@???
with a subject '1234' is reworked so that it is sent to 1234@??? and the
subject is given 'myfaxcode'.

My attempt is horribly ineffective. I'm having trouble grabbing the original
subject apart from anything else.

    fax_redirect:
      local_parts = faxout
      domains = faxing.net
      headers_remove = Subject
      headers_add = X-Original-Subject: $h_Subject\nSubject: myfaxcode
      driver = redirect
      data = $h_Subject@???

--
Rory Campbell-Lange
<rory@???>
<www.campbell-lange.net>